1. Field of the Invention
The present invention relates to the novel dihydropyridine, especially 1,4-dihydropyridine having an alkoxymethyl ester or alkylthiomethyl ester group at the 3-position, which is useful as anti-ischaemic and anti-hypertensive agents.
2. Description of the Background
The compound of the formula(I) is much useful as anti-ischaemic and anti-hypertensive agents. ##STR2## wherein R.sup.1 represents a phenyl group, which may be substituted by one or two substitutents selected from halogeno, nitro, trifluoro methyl and difluoromethoxy group, or 2,1,3-benzoxadiazole-4-yl group, R.sup.2 represents a lower alkyl or phenyl group, R.sup.3 represents a lower alkyl group and Y represents an oxygen or sulfur atom.
The term "aryl" as used in this specification includes, for example, phenyl which may be substituted by one or two substitutents selected from halogeno, nitro, trifluoromethyl and difluoromethoxy group. "Halogeno" means fluoro, chloro, bromo or iodo.
The term "lower" used in connection with an alkyl group is intended to mean the one having 1 to 4 carbon atom. "Lower Alkyl" may be ones having a straight or branched and saturated hydrocarbon chain such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl or t-butyl.
It is disclosed that the compounds substituted by alkoxyethyl ester and alkylthioethyl ester group at the 3-position reduce the intracellular movement of calcium ion and have an ability to reduce the blood pressure(cf. Spanish Laid Open Publication No. 537,427 and Ger. Offenlegungsschrift DE 2,747,513, Al).
The 1,4-dihydropyridine derivatives described above when used in anti-ischaemic and anti-hypertensive agents are not completely satisfactory as an excellent anti-ischaemic and anti-hypertensive agents.
Therefore, the development of an anti-ischaemic and anti-hypertensive agents possessing stability as well as an excellent effect has been desired.
In view of such circumstances, the inventors of the present invention synthesized a number of compounds and examined their pharmacological effects. As a result of these investigations, it was found that the 1,4-dihydropyridine derivative substituted by alkoxymethyl ester or alkylthiomethyl ester group at the 3-position shown by the following formula(I) fulfilled the above conditions and possessed an excellent anti-ischaemic and anti-hypertensive effect.